1. Field of the Invention
The present application generally relates to a method and an arrangement for ascertaining the relative position of at least two stations by means of radio location.
2. Related Art
Local radio location systems for determining the position of one or more mobile radio modules are widely used today. Methods using radio waves are distinguished by properties such as robustness, accuracy and insensitivity toward interfering and environmental influences.
One example of the application of such a radio location system is the automotive industry. With an eye toward the increasing importance of electromobility, electric vehicles are expected to be able to travel automatically and park with a high level of precision. The inductive charging of such electric vehicles, involves a high level of parking accuracy in order to orient the corresponding charging coils of the charging post and the electric vehicle to one another in a precise manner.
Such coordination involves not only measurement of the intervals between two objects equipped with radio modules, such as the electric vehicle and the charging post, but also determination of the angular position relative to one another. To that end, metrology is used to record the geometric complete relative position in terms of distance and angle. Only then is it possible for a regulatory system to undertake navigation of a vehicle. This is also known as “electronic towbar”.
Further opportunities for application arise by way of example in the field of loading bulk goods such as in strip-mining or in agriculture. Conventional radio location systems can obtain position information for a mobile unit from various measurable variables for the wave propagation between the mobile unit and base stations. For Example, these variables may be reception field strength, propagation time, propagation time differences or angle information for the signal arriving at a base station. However, the radio modules in the mobile unit and in the base stations are technically complex and hence expensive in this case.
The EP 0 567 888 A2 reference discloses a communication system for data transmission from a moving vehicle to a fixed beacon that has a transmission and reception device. In this case, a signal is emitted by the beacon and received by an antenna of an onboard appliance of the vehicle and, following modulation with a data signal, returned to the beacon again, where the data are extracted from the returned signal. The onboard appliance has at least two modulators that can be used independently of one another to modulate the received signal with the data signal and to return it in different ways.